Adding using to ActionT

Adding using to ActionT
This is a naive one, but it pops up more often than you think:

```
scala> :paste
:paste
// Entering paste mode (ctrl-D to finish)

val x = List(Some(1), Some(2))
val y = Right(1) :: x
val z = for { (a, b) <- y } yield a

// Exiting paste mode, now interpreting.

x: List[Some[Int]] = List(Some(1), Some(2))
y: List[Product with Serializable] = List(Right(1), Some(1), Some(2))
z: List[Any] = List()
```